Engine crankshaft position recognition and tracking is an important part of measurement of engine operating conditions. Today's engine control units (ECUs) rely upon real time measurements of crankshaft position for various engine crankshaft-sensitive functions, such as ignition, injection, cylinder cut, engine speed measurement, injection and ignition timing measurements.
To perform precise engine control, crankshaft position-sensitive commands need to be synchronized with the crankshaft position in angle domain. Therefore, the ECU must recognize and track the position of the crankshaft in the angle domain in real-time.
A combination of cam signals and crankshaft signals is used to recognize and track the engine crankshaft position. Engine and vehicle manufacturers have invented various cam and crankshaft signal patterns. These patterns are designed to allow the ECU to recognize the crankshaft position quickly once the crankshaft is rotated by the starter, as well as to track the crankshaft position accurately while the engine is running.